Completely viable. At least for PvE. Many have shifted to a more hybridized form of the build for PvP.
I can list some PvP specs if that was the basis for the question otherwise I recommend the build for any PvE content.
I too would like to know what a good PvE leveling spec would be. Of course mixed with some PvP for face melting fun.
Also my main is a sage healer and I am currently having him set up to be bio chem, for quick instant pocket heal and power/wil buffs. what do you all recommend for a shadow for crafting?